Review: BTY AA 2500mAh 1.2V Ni-MH Rechargable Battery

Rechargeable batteries are a great way of saving money. Especially these days where electronic devises are everywhere.

I’ve used many makes of battery from expensive top brands to unbranded imports.

My recent purchase was 24 BTY batteries purchased from a seller on eBay. I have no connection to anyone selling these batteries and this is a completely independent review.

Quite often imports from Hong Kong are unbranded products re-branded to be appealing to Western buyers. It’s prudent to take any brands and rated capacities with a pinch of salt and deciding if you want to take the risk or not.

These batteries cost under £1 each including delivery. The best I’ve seen them for is £3.47 for 4 delivered.

The batteries have a claimed capacity of 2500mAh. This is an important figure as it pitches itself with the higher capacity branded batteries at budget prices.

Each battery weighs 18 grams. This is far less than the 27grams that my 2100mAh Energizer batteries weigh.

Tests

I performed a number if test cycles with these batteries using 2 different methods

Method 1:

My first tests were done using my hobby charger (iMax B6). This charger is capable of charging all types of batteries (Lead Acid, NiCd, NiMH, Lipo). I performed an automated discharge, charge cycle 5 times, first on a single cell and then on 8 cells in series.

The charging rate on a single cell was 100 milliamps. This is about the same as a standard domestic charger would use. The charge on the 8 cells was set to max at 1000 milliamp. The charger will automatically use the best amp rating depending on how the batteries take it. Most of the time it was charging at 100 milliamps or lower per cell.

Method 2:

I have a Energizer wall socket charger. This charger is able to charge 2 or 4 cells at a time. A companion cell was added when charging to create 2 cells. The charging rate is between 170 and 190 milliamps. The batteries were left on charge until the charging light was extinguished. The manual for the charger does not state what actually determines when the charging completed so it may be timed or delta peak there is no way of telling. As this charger does not show how many miliamps were put into the battery the iMax charger was used to drain the battery to 0.5V for the capacity measurement.

Results

Method 1 (Single Cell)

The average capacity that was inserted into the single cell in method 1 was 813 miliamps. the battery was never above room temperature. This makes me believe that a greater charging rate is achievable and perhaps a greater capacity. The charger looks for a delta peak and will stop as soon as it detects this.

The capacity for each of the 5 charges was:

767

743

789

879

890

It is worth noting that the capacity of the battery was growing in a positive manner with each charge after the initial discharge. It is quite possible that this will increase over time but it’s uncertain if the stated capacity will ever be achievable.

Method 1 (8 cells)

The same test was performed using 8 cells in series. All the batteries were drained down to 0.5v before the tests were performed.

The total capacity and the individual cell capacity is shown in the results below.

6984 /8 = 873

8088 /8 = 1011

9704 /8 = 1213

7984 /8 = 998

8504 /8 = 1083

Method 2 (2 cell)

The batteries showed the following charged capacities following the Energizer charger.

1798 /2 = 899

1925 /2= 962

1987 /2= 993

2021 /2=1010

1932 /2= 966

It’s obvious to see that the batteries are retaining a greater charge using the unsophisticated Energizer charger over the iMax charger when charged in small quantities. This is quite a surprise. The iMax charger must be to sensitive when looking for the delta peak and the batteries are able to retain charge after this initial peak has been met.

Charge Comparisons

Summary

Are these batteries any good?

If you purchase these batteries for high drain devices then I’d say no. They don’t hold anywhere near the quoted capacity.

Are the batteries worth the money?

Considering the cost of non rechargeable batteries then I believe that you could get some high cost savings over time with these batteries. If these batteries were compared to other low price rechargeables then I believe they would hold there own as they are still cheap.

Most people who will buy these are buying batteries for high drain appliances like digital cameras. I don’t believe you’ll get much from these when used in this way.

I’ve been using my as transmitter batteries for my RC cars. In this setup I use 8 of these batteries at a medium drain in a 2.4Ghz transmitter. I use the transmitter 5 days a week for an hour and I get 2 weeks usage before they start to show a voltage drop. I charge the batteries in the transmitter using my Imax charger and it’s very convenient.

I have 4 others in 2 Nintendo Wii controllers. I’ve never run out of power even after a 8 hour session so they are perfect for saving money in this way. I charge them after a session and have not had issue with them ever running low.

If you require High Drain batteries then buy some Energizers. If you have a load of devices and are fed up buying batteries then these are ideal.

It’s not a stupid question. High drain items are things like digital cameras, camcorders, some games controllers, remote control toys.
In reality anything where you put a set of new batteries in and before you know it they are drained.

Thanks for the comment. I’m working on a number of reviews at the moment so check back sometime.

woot, thank you! I’ve finally came across a website where the owner knows what they’re talking about. You know how many results are in Google when I check.. too many! It’s so annoying having to go from page after page after page, wasting my day away with tons of owners just copying eachother’s articles… ugh. Anyway, thankyou for the information anyway, much appreciated.

Great review – thanks.
Just purchased 12 off 3000mah btys via ebay.
Running tests at present, using a Garmin GPS, which has a timer which runs until the batteries are dead – but it stores the time.
My 2500ma Encore batteries lasted 28 hours.
2 samples of the BTY 3000ma batteries lasted 8 hours!!
I’m continuing with tests – and expect to make a loud protest – Ebay should not permit fakes, ones they’ve been adequately reported.